Average CsI Neutron Density Distribution from COHERENT Data.

Using the coherent elastic neutrino-nucleus scattering data of the COHERENT experiment, we determine for the first time the average neutron rms radius of 133Cs and 127I. We obtain the practically model-independent value Rn=5.5+0.9-1.1 fm using the symmetrized Fermi and Helm form factors. We also point out that the COHERENT data show a 2.3σ evidence of the nuclear structure suppression of the full coherence. [ABSTRACT FROM AUTHOR]